This disclosure relates to a safety device adapted to be placed between a hoisting rope and a tie back attachment point when the hoisting rope is not in use. The hoist rope is typically part of a hoisting machine, such as a crane or an electric mining shovel.
Crane ropes with overhaul balls, lift blocks or end rigging at the end of hoist ropes are usually secured or tied back to the structure of the crane when not in use, or when transporting the crane. The purpose of the tie back is to prevent injury to personnel or damage to crane components resulting from uncontrolled swinging of the crane hook or rigging.
It is a relatively common situation, where a crane operator, due to some temporary inattentiveness, does not remove the tied back line or forgets that such lines are tied back by some type of rigging, and begins to advance or raise the boom or line on a RT crane, or boom down or advance the line on a crawler crane. This causes the secured line or rigging or structure to break once its ultimate fracture strength is exceeded. When this happens, part of the hoist machine rigging can be released and fly through the air with destructive force.
It is therefore advantageous to provide an indication to the crane operator, to forewarn the crane carrier operator, and any bystanders, of a potentially destructive and dangerous situation involving an overload condition.